Load bearing structures have used trusses and the like for years. Common occurrences of trusses include the use of trusses for rooflines in residential housing, commercial space, and the like. Most common rooflines, for example, use wooden trusses joined by plates having a number of spiked protrusions, similar to nails.
More and more, metal trusses are being used instead of wooden trusses for a variety of reasons. FIGS. 1 and 2 show sample metal trusses 100 and 200. Metal truss 100 comprises a plurality of chords 102 and a plurality of webs 104. As can be seen in FIG. 1, chords 102 are made of two tubular members spaced apart to provide an area 106 between the chords 102. A portion of each web 104 resides in area 106 between chords 102. The portion of web 104 fits into area 106 such that a conventional fastener 108, such as a screw or bolt, connects web 104 and chord 102. Metal trusses of this early type are shown in U.S. Pat. No. 4,253,210, title METAL TRUSS STRUCTURE, issued Mar. 3, 1981, to Racicot, incorporated herein by reference.
One obvious deficiency with metal truss 100 is that two tubular members are necessary to form area 106 into which web 104 is placed. FIG. 2 shows another prior art, metal truss 200. Metal truss 200 comprises a plurality of chords 202 and webs 204. In metal truss 200, chords 202 are U shaped and form channel 206. Thus, instead of using a plurality of tubular members to make area 104 into which webs can be placed, each U shaped chord 202 has an open end 208 such that the sidewalls 210 of chord 202 form channel 206. Webs 204 can be placed in channel 206 and connected to U shaped chords 202 using a conventional fastener 212, such as a bolt or screw. The term U shaped chord is generically used to mean any channel shaped chord. Similar to metal truss 100, chords 202 and webs 204 are connected using a conventional fastener 212, such as a screw or bolt. Metal trusses of this type are shown in U.S. Pat. No. 4,435,940, titled METAL BUILDING TRUSS, issued on Mar. 13, 1984, to Davenport et al., incorporated herein by reference.
The trusses described above can exist as independent structures or combined into carrying trusses and carried trusses. One difficulty discovered using carried and carrying metal trusses involved stabilizing carried trusses to the carrying truss. For example, FIG. 3 refers to a truss assembly 300 having a carrying truss 302 (commonly referred to as a girder) and a plurality of carried truss 304 (commonly referred to as jacks). Carrying truss 302 and carried truss 304 each are composed of chords 306 and webs 308. As can be appreciated, placing and stabilizing carried trusses 304 prior to attachment to carrying truss 302 is difficult.
In order to facilitate manufacture and erection of truss assembly 300 by stabilizing carried truss 304 about carrying truss 302, a special metal holder 310 was developed as shown in FIG. 4. Referring specifically to FIG. 4, chords 402 and webs 404 are shown. Chords 402 are conventional metal U shaped chords having a conventional channel 406 to facilitate in joining chords 402 and webs 404. Metal holder 310 includes shop installed fasteners 408 connecting metal holder 310 to webs 404 and chord 402. Metal holder 310 has a plate hook 410 formed by a slot 412 and extension 414 on metal holder 310. Extension 414 extends into channel 406 such that a sidewall 416 on chord 402 resides in slot 412. Metal holder 310 assists to stabilize carried truss 304 until it can be connected to carrying truss 302 using field installed conventional fasteners 418, such as screws or bolts. This type of temporary holding piece is further described in U.S. Pat. No. 5,806,265, titled METAL TRUSS JOINING GUSSET, issued on Sep. 15, 1998 to Sluiter, incorporated herein by reference.
Since the development of the early metal trusses using metal U shaped chords, metal trusses have continued to use channel shaped designs to form channels by which the webs and chords can be connected. Channel shaped chords have many disadvantages, including, without limitation, a limit of the strength of the member imposed by the fact that it is channel shaped. Thus, it would be desirous to develop apparatuses and methods that would facilitate the manufacture and erection of trusses using closed tubular members instead of channel shaped chords.